Free piston machine provided with pneumatic starting means



Feb. 22, 1949. H. B. HORGEN 2,452,745

FREE PISTON MACHINE PROVIDED WITH PNEUMATIC STARTING MEANS Filed April l1, 1945 Patented Feb. 22, 1949 FREE PISTON MACHINE PROVIDED WITH PNEUMATIC STARTING MEANS Belge Bodvar llorgen, Lyon, France, assignor, by direct and mesne assignments, of nine-tenths to Raul Patel-as Pescara, Lisbon, Portugal, and one-tenth to Societe dEtudes et de Participations, Eau, Gal, Electricite, Energie S. A., Geneva, Switzerland, a society of Switzerland Application April 11, 1945, Serial No. 587,897 In France May 30, 1944 12 Claims.

ing spaces, especially during the starting period.'

Another vobject of my invention is to provide means for safely ensuring, in operation, the due closing of the valve that controls the feed of starting air to the starting space or spaces of the machine.

The invention is to be applied more especially, but not exclusively, to motor compressors and free piston auto-generators, that is to say machines for feeding a gas under pressure.

Preferred embodiments of the present invention will be hereinafter described with reference to the accompanying drawing, given merely by way of example. and in which:

Fig. 1 is a diagrammatic axial sectional view of a free piston auto-generator provided with a starting device made according to the present invention; and

Fig. 2 shows a modication.

The machine shown by the drawing includes a motor cylinder I in which move two pistons 2 and coacting respectively. when they get close to the outer ends of their strolges, with inlet and outlets ports 3 and 4, respectively.

Each of these motor pistons carries a compressor piston, 5, 50 respectively, and these compressor pistons move in compressor cylinders 6, 60, respectively, so as to ensure, on their inner sides, through inlet and discharge valves 1 and 8 respectively, the feed of air under pressure to a iluidtight casing 9 which surrounds cylinder I.

These two sets of pistons are caused to move in synchronism through any suitable means (not shown in the drawing as having no direct bearing on the object of my invention).

During the outward (energy producing) strokes of the pistons, energy is stored up in the energy accumulators A, A, constituted by chambers of variable volume limited by the outer faces of pistons 5, 50 and the uid tight ends of cylinders 6, 80.

This machine is, of course, provided with fuel injection means, not shown by the drawing, as usual.

The energy accumulators A, A serve also to receive the starting air. They therefore constitute what I will call the starting spaces. For this purpose, I provide a conduit 23 located on the inside of the machine and eccentrically with respect to the axis thereof, the ends of this conduit extending through the compressor pistons 5, 50, which are therefore slidingly guided by this conduit. Said conduit is, for instance, fixed to the walls that carry discharge valves l. It is open at both ends and therefore affords constant communication between accumulators A and A, whereby the pressures in these accumulators are always practically equal.

To this conduit 23 is connected, through a conduit 22, the starting device, which includes a valve Iii adapted to control the communication between a starting air reservoir I I and the inside of saidconduit. Valve III is rigid with a piston I2 movable in a cylinder Il. The chamber Il' of this cylinder that is located on the side of piston I2 opposed to valve III may at will be connected, through a valve I5 or the like, either with a source I6 of gas under pressure or with the atmosphere. A spring I1 tends to keep valve III inthe closed position. A conduit I8, provided for instance in piston I2, with a check valve Il, permits the ow of gas from chamber I4 toward reservoir Il, but not in the opposed direction.

If the source I6 of air under pressure is connected, through valve I5, with chamber I4, valve III remains closed and air under pressure passes through conduit I8 into reservoir Il, which is thus lled. It now suffices, by acting on valve I5, to bring chamber I4 into communication with -the atmosphere for causing valve Il and piston I2 to be moved in the upward direction under the effect of the pressure existing in reservoir Il. Valve III is thus opened and the starting air is fed to the accumulators and causes the machine to start. The pressures existing in these accumulators A0 and A, and consequently the starting forces brought into playV on either side of the machine are always respectively equal, owing to the constant communication constituted by conduit 2l.

In order to obtain the above described operation, valve I5 is arranged in such manner as to permit: o

a.- in position I, of filling reservoir I I as above set forth;

b.- in position In, of bringing chamber I4 linto communication with the atmosphere; and

c.- in position II, of placing this chamber I4 Shown by Fig. 1).

out of communication both with source I5 and the atmosphere.

As the spring I1 which serves to close valve I Il is generally notvery strong, it cannot be relied upon with suiiicient safety to close` this valve once the starting air has been introduced into the starting spaces and valve I5 has zbeen broughtdnto position II. For this reason, in order to close valve I after the bringing of valve I into position II, the starting device is fitted with a conduit 20, provided with a check valve 2|, adapted to permit the ow of gas from accumulators A0, A toward chamber I4, but not in the opposed direction. Preferably, a weak spring is provided for applying check valve 2| against its seat.

Conduit 20, together with its check valve 2| acts as follows: l

As soon as valve I5 is in position II, chamber I4 is filled, through conduit 20 and past valve 2|, with gas at a pressure which is the closer to the maximum pressure in accumulators A, A as the strength of the spring of check valve 2| is smaller. This pressure, including the pressure exerted by spring I1, brings valve I0 back to its closed position and safely keeps it in this position if the spring that applies valve |9 against its seat is suillciently strong for creating,'between the two sides of piston I2, the necessary pressure dierence.

Furthermore, the gas under pressure fromthe accumulators will pass from chamber I4 into reservoir II through conduit I8 and past check valve I9. This reservoir will thus be charged to a pressure close to the maximum pressure ofthe accumulators, whereby the consumption of starting air will be lower than if reservoir II remained empty between two startings of the machine. v According to a particularly advantageous embodiment of my invention, I fit on conduit23, which constantly connects together the energy accumulators, not only the starting inlet device, but also a device for adjusting the pressures in said accumulators. 'I'his last mentioned device operates by varying, in response to variations of a working pressure of the machine (for instance the discharge or delivery pressure of the compressor portion ofthe machine) the weight of air present in the machine accumulators.

Preferably, the above mentioned devices for admitting starting air and for regulating the pressure in the accumulators are grouped into a single system carried by an element 24 which closes in a fluid tight manner an aperture provided in the lateral wall of casing 9.

The regulating device above referred to advantageously includes a piston valve 25 movable in a. cylinder 26 in communication at both ends with the inside of casing 9. 'Ihis slide valve includes'two chambers 25, 25, respectively provided with ports 26, 26 adapted to coact with a fixed aperture provided in cylinder 26, at 21, and in communication with conduit 22, this aperture 21 being closed in the neutral, or intermediate, position of piston valve 25 (position In a wall of chamber 25 are provided apertures controlled by check valves 29 adapted to permit air to ow from chamber 25 into casing 9, whereas, in a wall of chamber 25 are provided apertures controlled by check va1ves`28 adapted to permit the ilow of air from casing 9 into chamber 25.

This piston valve 2 5 is connected to a piston 29 slidably mounted in a cylinder 30. One of the faces of said piston is subjected to the pressure existing in casing 9. this pressure being transmitted through aconduit 3|. The other face of the piston is subjected to the mean pressure of the accumulators transmitted through a conduit 32 of very small section directly connected with a conduit 20 in communication with conduit 22.

A spring 33 is provided to push piston 29 in the same direction as the pressure transmitted from casing 9.

The whole is arrangedv in such manner that a rise of the working pressure, other things being the same, causes port 26'J to be brought opposite aperture 21, and that, on the other hand, a drop of this pressure causes port 26,to be brought opposite this aperture 21. As soon as the mean pressure of the accumulators has assumed the value that corresponds to the working pressure of the machine, piston valve 25 is brought back into neutral position.

Therefore, when the working pressure rises, air passes from casing 9 into the accumlators, and vice-versa, provided, of course, that the curve of variation of the pressure in the 4accumulators is such that the working pressure has a value ranging between the extreme values of the pressures in the accumulators.

The operation of this devicey will be analogous when the mean pressure of the accumulators, and not the working pressure, undergoes a variation, with the only difference that the direction of displacement of the slide valve is reversed.

Finally, I may also provide a valve 34 adapted. when it is desired, previous to the starting of the machine.- to bring the pistons into the position that corresponds to this starting, to place the inside of the accumulators into communication with the atmosphere. Advantageously, this valve will be disposed on the wall of conduit 22 and arranged in such manner as to open inwardly when a piston 35, asociated with said valve 34, is subjected to the action of compressed air fed through a tube 36 controlled through a valve located within reach of the operators hand.

'I'his valve 34, together with its piston 35 is advantageously included in the system above described, constituted by the starting and regulating devices, so that no supplementary condui will be necessary.

Inl the apparatus illustrated by Fig. 1, the starting air inlet device is locatedlIvsubstantially in the middle part of the machine. But in some cases it may be of interestI to iit this device on the end of one of the accumulators, as shown by Fig. 2, in which this device is designated by reference character B.

In this case, there exists a considerable `dif-- ference between the. distances which separate this device B from the accumulators A0 and A09. respectively. In order to obtain, despite this difference, substantially the same loss of pressure between device B and each of the accumulators, so that these accumulatorsdevelop the same work when starting the machine, it is advantageous to make use of the special arrangement illustrated by Fig. 2. According to this arrangement, one of the portions of the communlcation conduit through which-the starting air is fed to the accumulators, to witthe portion between the feed of air and the accumulator located in close vicinity with the starting air inlet device B. is throttled or otherwise made of a motor cylinder, two motor lpistons freely movable in said cylinder in synchronism with each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted to coact with the corresponding piston, means for permanently connecting together said starting spaces, a single starting device for feeding gas under pressure to said last mentioned means, and

a check valve between said starting vdevice and said conduit means, opening toward said conduit means.

In the embodiment illustrated by Fig. 2, I

provide, between the starting air inlet device and the communication conduit 23.23, a check valve 31 which allows starting air to ow only toward the accumulators. The presence of this check valve prevents gas interchanges, to be avoided in operation, between the communication conduit and the starting air inlet device, especially when the starting device is not provided with means for ensuring, after starting the closing of valve I0 (as in the case of Fig. l).

An analogous check valve might of course be provided in the device of Fig. 1.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and'l emcient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the ap# pended claims.

What I claim is:

l. A machine which comprises, in combinatio a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means associated with each of said pistonsY for the pneumatic starting of said machine, each of said means forming a starting space adapted'to coact with the corresponding piston, conduit means for permanently connecting to-l gether said starting spaces, and a single'starting device for feeding gas under pressure to a point of said conduit means, the portions of said conduit means that extend from this point to said starting'spaces respectively being of different lengths andthe shorter one having at 4. A machine which comprises, in combination, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting 1 space adapted to coact with the corresponding movable in said cylinder in synchronism with l each other, means associated with each of said least a part of smaller cross section than the other, so as to equalize the respective pressurev drops therethrough.

2. A machine which comprises, inv combina` ,l tion, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted to coact vwith'the corresponding piston, said starting spaces being arranged to contain gas cushions so as to act as pneumatic energy accumulators for ensuring the inwardstroke displacements 'of said pistons, conduit means for permanentlyv connecting together said starting piston, said starting spaces beingarranged to contain gas cushions so as to act as pneumatic energy accumulators for ensuring the inward stroke displacements of said pistons, conduit means for permanently connecting together said starting spaces, a single starting device for feeding gas under pressure to said conduit means, and a check valve between said starting device and said conduit means, opening toward said conduit means.

5. A machine which comprises, in combination, a motor cylinder, two motor pistonsfreely movable in said cylinder in synchronism with each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted tov coact with the corresponding piston, conduit means for permanently connecting together said starting spaces, a` single starting device for feeding gas under pressure to a point, of said conduit means, the portions offsaid conduit means that extend from this point to said start- Aing spaces respectively being of 'diierent lengths and'the shorter one having at least a part of smaller cross section than the other, so as to equalizel the respective pressure drops therethrough, and a check valve between said starting device and said conduit means, opening toward said conduit means.

,6. A machine which comprises, in combination, a motor cylinder, two motor pistons freely pistons for the pneumatic starting of said machine, each of said means forming a .starting space adapted to coact with the corresponding piston, said starting spaces being arranged to con- .tairi gas cushions so as to act as pneumatic energy accumulators for ensuring the inward stroke spaces, and a single starting device for feeding gas under pressure to a point of said conduit means, the portions of said conduit means that extend from -this point to said starting spaces respectively being of different lengths and the.

shorter one having at least a part of smaller cross section than the other, so as to equalize the respective pressure drops therethrough.

3. A machine which comprises, in combination,

vdisplacements of said pistons, conduit means for permanently connecting together said startingv spaces, a single starting device for feeding gas under pressure to a point of said conduit means, the portions of said conduit means that extend from this point to said starting spaces respectively being of diiferent lengths and the shorter one having at least a..part of smaller cross. section than the other, so as to equalize the respective pressure drops therethrough, and a check valve between said starting device and said conduit means, opening toward said conduit means.

'1. A machine which comprises, in combination, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means, including a compressor piston,A associated with each of said motor pistons y for the pneumatic starting of said machine,leach of said means forming a starting space adapted to coact with the corresponding pistons, aconduit for permanently connecting together said starting spaces, said conduit extending through coact with the piston, a reservoir for feeding Agas under pressure to said starting space, a valve said compressor pistons and being arranged to act as eccentric guiding means for said compressor pistons, and a single starting device for feeding gas under pressure to said conduit means.

8. A machine which comprises, in combination, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means, including a compressor `piston, associated with each of said motor pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted to coact with the corresponding pistons, said starting spaces being arranged to contain `gas cushions so as to act as pneumatic energy accumulators for ensuring the inward stroke displacements of said pistons, a conduit for permanently connecting together said starting spaces, said conduit extending through said compressor pistons and being adapted to constitute eccentric guiding means for said compressor pistons, and a single starting device for feeding gas under pressure to said conduit means. Y i

9. A machine vwhich comprises, in combination, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with 'each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted to coact with the corresponding piston, said starting spaces being arranged to contain gas cushions so as to act as pneumatic energy accumulators for ensuring the inward stroke displacementsof said pistons, conduit means for permanently connecting together said starting spaces, a single starting device for feeding gas under pressure to said conduit means, and a device for regulating the weight of air of said energy accumulators opening into said conduit means, said two last mentioned devices being grouped into a single unit.

10. A machine which comprises, in combina-v tion, a motor cylinder, two motor pistons freely movable in said cylinder in synchronism with each other, means associated with each of said pistons for the pneumatic starting of said machine, each of said means forming a starting space adapted to coact with the corresponding piston, means located within said machine for permanently connecting together said starting spaces, and a single starting device for feeding gas under pressure to said last mentioned means.

11. A machine which comprises, in combination, a motor cylinder, at least one motor piston freely movable in said cylinder, means associated with said piston for starting said machine, said means forming a starting space adapted to interposed between said reservoir and said starting space for controlling the communication -between them, a cylinder communicating at one end with said reservoir and closed at the otherv end, a piston in said last mentioned cylinder,

valve means for connecting the chamber existing between the last mentioned piston and the closed end `vof the corresponding cylinder either with a source of compressed gas or with a medium at lower pressure, conduit means extending across said last mentioned piston for connecting said chamber with said reservoir, a check Valve in said conduit means opening toward* said reservoir, means insaid machine forming a space filled with gas under pressure, conduit means -between said last mentioned space and said chamber, and a check valve in said last mentioned conduit means, said last mentioned check valve lopening toward said chamber. f

12. A machine -which comprises, in combination, a motor cylinder, at least one motor piston freely movable in said cylinder, means associated with said piston for starting said machine, said means forming a starting space adapted to coact with the piston, a reservoir for feeding gas under pressure to said starting space, a valve interposed between said reservoir and said starting space for controlling the communication between them, a cylinder ycommunicating at one end withv said reservoir and closed at the other end, a piston in said last mentioned cylinder, valve means for connecting the chamber existing between the last mentioned piston and the closed end of the corresponding cylinder either with a source of compressed gas or with a medium at lower pressure, conduit means extending across said last mentioned piston for connecting said chamber with said reservoir, a check valve in, said conduit means opening toward said reservoir, conduit vmeans between said starting space and said chamber, and a check valve in said last mentioned conduit means, said last mentioned check valve opening toward said chamber.

HELGE BODVAR HORGEN.

REFERENCES CITED The following references are of'record in the file of this patent: f

UNITED STATES PATENTS FOREIGN PATENTS -Country Date v Great Britain Oct. 6, 1943 Number Number 

